Vintage Chemistry at Stranmillis
The next time you sip a chilled Chardonnay or gaze lovingly at a full-bodied Merlot, spare a thought for what exactly is in your glass and why it is there. The chemical analysis of wine was the focus of this year’s ‘Schools’ Analyst Competition’ held recently (before the lockdown!) at Stranmillis University College Belfast.
The event, organised by the Analytical Division of the Royal Society of Chemistry, aims to showcase the important role that analytical chemistry plays in the pharmaceutical industry, the regulation of standards for food and drink and the monitoring of the environment. The methods of analysis all relate to the A-level chemistry curriculum and the pupils are assessed on their accuracy, precision and ability to work as a team.
This year the competition was generously sponsored by local entrepreneur Dr Terry Cross OBE, owner of Château de La Ligne in Bordeaux, and featured the analysis of the white wine Marquis de la Ligne Bordeaux Blanc.
Teams of three sixth-form pupils representing 13 schools from across Northern Ireland competed to produce the most accurate determination of the wine’s acid content, sulphur dioxide levels and concentration of iron. The principal acid present in grapes is tartaric acid which gives the wine a tart taste.
The amount of acid present in wine varies and depends on the region the wine comes from, the climate the grapes were exposed to, and the conditions during fermentation. As the acid content influences the taste of the wine it is closely monitored and can be altered by addition of the base potassium hydrogen carbonate. Sulphur dioxide or sulphites are added to wine as a preservative to inhibit the growth of microorganisms and therefore ensure that the wine is safer to drink.
Sulphite is also an antioxidant and prevents the deterioration of flavour and discolouration by inhibiting both enzymic and non-enzymic browning. Since sulphites are normal products of the human body’s metabolism, we are able to cope with them provided the levels are not too high. Therefore the amount of sulphite added to wine must be carefully regulated as, in very high concentrations, it can produce gastric irritation and destroy the essential nutrient thiamine (Vitamin B1). Wine also contains low levels of iron which is taken up from the soil by the vine as the grapes grow and mature.
The winning team from Lumen Christi College Derry was presented with their certificates and book tokens to the value of £200 Dr Terry Cross OBE. The pupils from Rainey Endowed School (£100) came a close second, followed by Belfast High School (£80) and Rathmore Grammar School (£60).
Terry praised the pupils’ practical skills and was particularly impressed at how they were able to put their knowledge of chemistry theory into practice. Addressing the pupils and their teachers he said, “As a business man and employer I am delighted to see high quality team work and problem-solving skills used in real-life scenarios. Our future economy relies on having the type of talented and dedicated young people I have observed here today.”
All of the participants were found to meet the required level of accuracy and precision in their analyses and so were each presented with a certificate to mark their attainment and a book token.
Finally, on considering the pupils’ finding that a standard glass of Marquis de la Ligne Bordeaux Blanc would only contribute 4% to the recommended daily intake of iron, fortified breakfast cereals, lentils and spinach remain a better and healthier option!
For more information on the competition please contact J.McCullagh@stran.ac.uk
Top photo caption:
(from left) Dr Michael Harriott (Chair of The NI Analytical Division of RSC), the winning team of Patrick Gormley, Sean Morrison and Lewis McGarrigle, and the event sponsor Mr Terry Cross, owner of Château de La Ligne in Bordeaux.
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